The invention relates to a device for automatic insertion and ejection of an information carrier, and more particularly to such a device comprising
a carrying element which cooperates with the information carrier, PA1 a slidable drive member which is moved by the carrying element and which stores energy in a return spring during insertion of an information carrier, and PA1 an over-center mechanism comprising a rotary drive member such as a rotatable gear member which cooperates with the slidable drive member and which is eccentrically coupled to a connecting rod, the rod having a remote end which is guided longitudinally and, PA1 an over-center spring which exerts a biasing force on the connecting rod via a control plate, which force is greater than that of the return spring, PA1 the over-center mechanism having a latched position when it is rotated beyond the over-center point. PA1 .rho. is the distance between each individual tooth center and the center of rotation of the spiral, PA1 .rho..sub.1 the distance between the tooth center of the first tooth and the center of rotation of the spiral, PA1 .rho..sub.x the distance between the center of the last tooth and the center of rotation of the spiral, PA1 B the developed length of the spiral gear and gear rack, EQU B=n.multidot.t=(z-1).multidot.t=(z-1)m.multidot..pi., PA1 z the number of teeth, PA1 t the pitch m.multidot..pi., PA1 m the module, PA1 n the number of teeth minus 1, PA1 .alpha..sub.x the angle between the first and the last tooth, PA1 .alpha..sub.i the angle between the first tooth and the tooth being considered, PA1 i the running index ##EQU3##
Such a device is known from German Patent No. 26 37 141, to which U.S. Pat. No. 4,071,859 corresponds. When a tape cassette is inserted into the cassette holder the cassette takes along a gear rack. As a result of this, a return spring connected to the rack is thus storing energy which will later be used to eject the cassette. As the cassette is inserted the rack rotates an over-center mechanism, which comprises a "crank" gear-wheel or pinion functioning as the rotary drive member which is in mesh with the rack, and a connecting rod which is coupled electrically to the pinion. As a result of the manual insertion of the cassette the over-center mechanism is rotated beyond its over-center point and the pretensioned connecting rod automatically rotates the pinion into a latched position upon passage of the over-center point. For this purpose the over-center spring which acts on the connecting rod must be stronger than the return spring of the rack. When the pinion is unlatched the over-center mechanism automatically moves the rack beyond the over-center point into the initial position under the influence of the return spring. As a result of this construction of an automatic insertion mechanism, the room at the front of the apparatus is not sufficient to accommodate further functional elements.